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Pteridospermatophyta, also called "pteridosperms" or "seed ferns" are a polyphyletic [1] grouping of extinct seed-producing plants. The earliest fossil evidence for plants of this type are the lyginopterids of late Devonian age. [ 2 ]
The first spermatophytes (literally: "seed plants") – that is, the first plants to bear true seeds – are called pteridosperms: literally, "seed ferns", so called because their foliage consisted of fern-like fronds, although they were not closely related to ferns. The oldest fossil evidence of seed plants is of Late Devonian age, and they ...
Cycads were also common, as were ginkgos and tree ferns in the forest. Smaller ferns were probably the dominant undergrowth. Caytoniaceous seed ferns were another group of important plants during this time and are thought to have been shrub to small-tree sized. [16] Ginkgo-like plants were particularly common in the mid- to high northern latitudes.
The Lyginopteridales are an extinct group of seed plants known from the Paleozoic.They were the first plant fossils to be described as pteridosperms (a polyphyletic group sometimes referred to as "seed ferns") and, thus, the group on which the concept of pteridosperms was first developed; [2] they are the stratigraphically oldest-known pteridosperms, occurring first in late Devonian strata; [3 ...
The Caytoniales (Figs. 1-2) are an extinct order of seed plants known from fossils collected throughout the Mesozoic Era, around 2] [3] [4] They are regarded as seed ferns because they are seed-bearing plants with fern-like leaves. [4]
This poses such a problem for the theory of gradual evolution that Charles Darwin called it an "abominable mystery". [5] Several groups of extinct gymnosperms, in particular seed ferns, have been proposed as the ancestors of flowering plants, but there is no continuous fossil evidence showing how flowers evolved. [6]
It is the archetypal genus of the corystosperms, an extinct group of seed plants, often called "seed ferns", assigned to the order Corystospermales or Umkomasiales. Species of Dicroidium, which grew as large trees, were widely distributed and dominant over Gondwana during the Triassic ( 252 to 201 million years ago ).
The Dicroidium plant (which bore Dicroidium leaves, Umkomasia seed bearing structures and Pteruchus pollen organs) is thought to have grown as large trees, with trunks at least 10 metres (33 ft) tall and over 50 centimetres (20 in) wide. [7] Some other possible corystosperms like Pachypteris may have grown as shrubs. [8]